Wideband Code Division Multiple Access (WCDMA) mobile wireless systems have enjoyed widespread uptake of high-quality circuit-switched applications like voice and video telephony. In a WCDMA system, downlink data transmissions are typically designed to be orthogonal at a transmitter. An orthogonal code st is used to combine and separate user data frames. However, the code orthogonality may be destroyed by multiple access interference (MAI) caused by, for example, multipath fading, multiuser interference, and/or interference from other cells, thereby resulting in significant inter-code/inter-path interference at a wireless communications receiver. MAI may result in a downlink data transmission reaching the wireless communications receiver by multipath. More than one replica of an original downlink data transmission may arrive at different time delay at the wireless communications receiver. The effects of multipath may comprise cross-interference of the downlink data transmission and/or phase shifting caused by varying transmission geographic lengths. In digital communications, multipath may also cause inter-symbol interference (ISI) errors and affect the quality of communications. Various sophisticated signal processing techniques such as equalization, orthogonal frequency division modulation, and/or RAKE receivers may be employed at the wireless communications receiver to mitigate or correct ISI for better quality of communications. A RAKE receiver may be used to counteract the effects of multipath using a plurality of correlators, each referred to as a finger. In a RAKE receiver, each finger tunes to a different multipath component of one original data transmission. The plurality of fingers may be combined to generate a single signal, typically having a higher signal-to-noise ratio than the separate signals. The generated single signal from the RAKE receiver may be further processed for channel decoding.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.